Question:

Describe how regular expression range character sets work and give at least one example of their usage.

The lone ranger

In regex we might like to target a range of charaters that are part of a certain family. For example we might want to target all numbers from 1 through 5 without having to type 1,2,3,4,5 out manually. So how do we do this?

Well we use our [] bracket notation with the - range charater like so: [1-5]. Now we are targeting all numbers from 1 through 5 with out having to do [1,2,3,4,5] out manually. Now doing this will only match the first number found but we can use a symbol like + to match at least one or more matches so [1-5]+ will pick match this string 12345. If you have a string such as 12349985 then will return 1234 and 5.

We can also have other variations such as [a-z] to target all lowercase letters or [A-Za-z]+ to target all lowercase and uppercase letters. We can also negate the values so that we target everything but those values.

  var pattern = /[^0-9]+/ig; 
  var text = '12super3499girl85'; 
  var matches = text.match(pattern);

 console.log(matches);
 // returns ['super', 'girl'];